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scsi: sbitmap: Add helpers for updating allocation hint

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Add helpers for updating allocation hint so that we can avoid duplicate
code.

Prepare for moving allocation hint into sbitmap.

Link: https://lore.kernel.org/r/20210122023317.687987-4-ming.lei@redhat.com
Cc: Omar Sandoval <osandov@fb.com>
Cc: Kashyap Desai <kashyap.desai@broadcom.com>
Cc: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Cc: Ewan D. Milne <emilne@redhat.com>
Cc: Hannes Reinecke <hare@suse.de>
Tested-by: Sumanesh Samanta <sumanesh.samanta@broadcom.com>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
This commit is contained in:
Ming Lei 2021-01-22 10:33:07 +08:00 committed by Martin K. Petersen
parent efe1f3a1d5
commit bf2c4282a1
1 changed files with 54 additions and 39 deletions
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93
lib/sbitmap.c
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@ -9,6 +9,55 @@
#include <linux/sbitmap.h>
#include <linux/seq_file.h>
static int init_alloc_hint(struct sbitmap_queue *sbq, gfp_t flags)
{
unsigned depth = sbq->sb.depth;
sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
if (!sbq->alloc_hint)
return -ENOMEM;
if (depth && !sbq->sb.round_robin) {
int i;
for_each_possible_cpu(i)
*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
}
return 0;
}
static inline unsigned update_alloc_hint_before_get(struct sbitmap_queue *sbq,
unsigned int depth)
{
unsigned hint;
hint = this_cpu_read(*sbq->alloc_hint);
if (unlikely(hint >= depth)) {
hint = depth ? prandom_u32() % depth : 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
return hint;
}
static inline void update_alloc_hint_after_get(struct sbitmap_queue *sbq,
unsigned int depth,
unsigned int hint,
unsigned int nr)
{
if (nr == -1) {
/* If the map is full, a hint won't do us much good. */
this_cpu_write(*sbq->alloc_hint, 0);
} else if (nr == hint || unlikely(sbq->sb.round_robin)) {
/* Only update the hint if we used it. */
hint = nr + 1;
if (hint >= depth - 1)
hint = 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
}
/*
* See if we have deferred clears that we can batch move
*/
@ -355,17 +404,11 @@ int sbitmap_queue_init_node(struct sbitmap_queue *sbq, unsigned int depth,
if (ret)
return ret;
sbq->alloc_hint = alloc_percpu_gfp(unsigned int, flags);
if (!sbq->alloc_hint) {
if (init_alloc_hint(sbq, flags) != 0) {
sbitmap_free(&sbq->sb);
return -ENOMEM;
}
if (depth && !round_robin) {
for_each_possible_cpu(i)
*per_cpu_ptr(sbq->alloc_hint, i) = prandom_u32() % depth;
}
sbq->min_shallow_depth = UINT_MAX;
sbq->wake_batch = sbq_calc_wake_batch(sbq, depth);
atomic_set(&sbq->wake_index, 0);
@ -418,24 +461,10 @@ int __sbitmap_queue_get(struct sbitmap_queue *sbq)
unsigned int hint, depth;
int nr;
hint = this_cpu_read(*sbq->alloc_hint);
depth = READ_ONCE(sbq->sb.depth);
if (unlikely(hint >= depth)) {
hint = depth ? prandom_u32() % depth : 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
hint = update_alloc_hint_before_get(sbq, depth);
nr = sbitmap_get(&sbq->sb, hint);
if (nr == -1) {
/* If the map is full, a hint won't do us much good. */
this_cpu_write(*sbq->alloc_hint, 0);
} else if (nr == hint || unlikely(sbq->sb.round_robin)) {
/* Only update the hint if we used it. */
hint = nr + 1;
if (hint >= depth - 1)
hint = 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
update_alloc_hint_after_get(sbq, depth, hint, nr);
return nr;
}
@ -449,24 +478,10 @@ int __sbitmap_queue_get_shallow(struct sbitmap_queue *sbq,
WARN_ON_ONCE(shallow_depth < sbq->min_shallow_depth);
hint = this_cpu_read(*sbq->alloc_hint);
depth = READ_ONCE(sbq->sb.depth);
if (unlikely(hint >= depth)) {
hint = depth ? prandom_u32() % depth : 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
hint = update_alloc_hint_before_get(sbq, depth);
nr = sbitmap_get_shallow(&sbq->sb, hint, shallow_depth);
if (nr == -1) {
/* If the map is full, a hint won't do us much good. */
this_cpu_write(*sbq->alloc_hint, 0);
} else if (nr == hint || unlikely(sbq->sb.round_robin)) {
/* Only update the hint if we used it. */
hint = nr + 1;
if (hint >= depth - 1)
hint = 0;
this_cpu_write(*sbq->alloc_hint, hint);
}
update_alloc_hint_after_get(sbq, depth, hint, nr);
return nr;
}